CSI creator Anthony Zuiker talked to THR about looking for the perfect woman to play Willows, and why Helgenberger was always his first choice:

"The inspiration for Marg Helgenberger's character, Catherine Willows, was a real CSI from Las Vegas named Yolanda McLeary. She was incredibly sexy and tough. She was the type of woman that could work the graveyard shift and then go out with the guys afterward for beers. They would rip her and joke around with her, and she would give it right back.

“The character's original name was Catherine Bellows. Once we began to talk more about her backstory -- she was a single mom who used to be a stripper, and she was holding this double life, being a parent and being a CSI -- we softened the last name to Willows, the metaphor being that willows are very beautiful yet very fragile underneath the veneer.

“We were looking for a TV star who could play an iconic role. I was a fan of Marg when she was on China Beach. When we first sat down with her, she had just wrapped Erin Brockovich. We were trying to find somebody who could stand the test of time in a special show -- someone who was sexy and tough and who had a lot of acting chops, someone to whom CBS' very important female audience could relate, someone with a high IQ rating and who had a great pedigree. We found all that in Marg. We had a shortlist of names that we were considering, but she was always our first choice. She had such a gung-ho spirit about the role.

“Hiring her was arguably the best decision we ever made. It was tough to see her go. I was there for the last scene and then later, when she said goodbye to the cast and crew. It was the end of an era with a special actress."